This invention relates to a piston ring such as used in internal combustion engines. There are presently two general approaches to piston ring design. The first approach uses a spacer expander ring to provide a spring type force to push the sealing ring against the cylinder wall to cause sealing. A ring of this type is shown in the Hartley Pat. No. 3,608,911 and utilizes a flexible plastic support that expands outward under the pressure of combustion gases to effect sealing. In the first approach, the mechanical spring loading is continuous and creates continuous undesirable friction losses. In the Prasse et al patent, the sealing force is proportional to the amount of gas pressure being applied to the seal but does not take into account frictional drag and other hydrodynamic forces that cause increased wear, friction and reduced sealing. Additionally, all traditional rings are split to allow for installation. The split construction forms an added path for the escape of gas by the ring.